Microelectronic packages include one or more dies fixed to a package substrate. A die is sometimes coupled to a package substrate using solder, where solder is disposed between the die and the package substrate and then exposed to heat, to reflow the solder. Once cooled, the die is fixed by the reflown solder.
Prior to completion of the reflow process, the die is free to move around. The die may move from movement or vibration of the package during handling, or during the reflow process when the solder is in a liquid state, allowing the die to float. This movement can be problematic in that performance of some devices (e.g., radio-frequency devices) may be tied to having precise and repeatable placement of the die in the package.
To restrict the movement of the die within the package prior to completion of the reflow process, pockets are sometimes formed in the package substrate, or precision-machined alignment plates are used. Using package substrates including pockets requires stocking custom-formed package substrates for various particular devices. Although the alignment plates allow for use of generic package substrates, removal of the plates after a die is fixed to the package substrate requires additional manual steps and sometimes results in damage to the die.